The present invention relates to a fastener. In particular, the present invention relates to a fastener, such as a screwdriver, having a switch assembly and gear assembly which can change from a standard driving speed application to a high diving speed application.
Traditional hand held screwdrivers maintain a direct relationship between the revolutions of the handle and the revolutions of the output shaft. This direct relationship results in fatigue and stress on the user's arm and wrists since each handle revolution results in only one revolution of the bit. Accordingly, the typical screwdriver produces a slow fastening process. Further, typical screwdrivers enhance the fatigue and stress in tight and/or difficult work areas having obstacles between the user and the work area. In these types of work areas, the user often adjusts positions of the hand/screwdriver to maneuver around the obstacles. With the direct revolution ratio, this maneuvering increases the time to complete the fastening process leading to increased fatigue and stress.
As demands for increased fastening production and improved quality escalate, a need exists for increasing the fastening process of screwdrivers. The solution, however, must minimize repetitive stress and fatigue injuries. Thus, a need exists for increasing the speed of the output shaft revolutions with respect to the speed of the handle revolutions. The solution, however, must also provide a standard speed of the output shaft to provide a higher torque to the screw.
Accordingly, a need exists for a screwdriver having a high driving speed application which increases the speed and reduces the torque to the screw being turned and having a slow driving speed application which reduces the speed and increases the torque to the screw being turned. The solution, though, must provide a convenient switch mechanism between the high driving speed and the standard driving speed applications. The solution must also provide a switch mechanism incorporating a minimum amount of parts wherein the parts must fit within a comfortable and ergonomic handle.
The prior art does not satisfy the needs and solutions required. Typical hand held screwdrivers provided a ratcheting feature which allows for free back turning. This ratcheting feature, though, does not increase the shaft revolutions as compared to the handle revolutions. Other tools are equipped with a torque control shut off clutch for power tools. These tools are equipped with a clutch mechanism that responds to the torque imparted by the tool to the fastener. When a set torque is reached, the clutch mechanism shuts off the motor from the bit terminating output to the shaft. Accordingly these tools relate to torque control and do not increase the shaft revolutions as compared to the handle revolutions.